Mission to Rescue US Hostages 'Flawless,' Except for Rescue

A large contingent of American special operations forces was able to sneak into an ISIS camp near the terror group's stronghold in Syria in search of American hostages, but quickly withdrew when it became clear that while 100 or so armed terrorists were there, the hostages weren't, according to a U.S. official with knowledge of the then-secret mission.

The official provided ABC News with new, dramatic details of the raid earlier this summer to grab Americans including journalist James Foley, a mission that Secretary of Defense Chuck Hagel said today was "flawless" except that no one was rescued.

"Knowing their lives were clearly in danger, it's the responsibility of our leaders, our government to take action when we believe there is a good possibility or chance of making the operation successful. This operation, by the way, was a flawless operation, but the hostages were not there," Secretary Chuck Hagel told reporters today. "We regret that mission did not succeed but I am very proud, very proud of the U.S. forces that participated in it."

The U.S. official familiar with the operation agreed that the mission, at least from a military perspective, was "magic."

When the "unusually large" U.S. special mission unit - described by senior officials as "several dozen" warfighters -- arrived at the location near Raqqah, Syria where they believed the hostages were being held, they had little time "on station" because of the distance they had to fly from their launch base.

A senior administration official said Wednesday that "while on site it became apparent the hostages were not there." But around 100 ISIS fighters were there, said the U.S. official familiar with the incident, and the American forces engaged in a fierce firefight. An Air Force AC-130 gunship came in overhead and put down fire on other ISIS fighters, keeping the bulk of the extremist force from the fight.

The Americans killed a number of ISIS fighters - at least 15, according to the U.S. official - before scrambling back to their helicopters and flying away.

The official said that some in the military and intelligence circles believe they missed the hostages by less than a week.

"It was magic," the official told ABC News today. "Everything went perfectly and [there were] no major injuries... But they saw it was a dry hole and left."

Today Hagel declined to blame the incident on an intelligence failure.

"Was it a failure of intelligence? No. Intelligence doesn't come wrapped in a package with a bow. It's a mosaic of many pictures, of many factors, and the enemy always has a say," Hagel said. "The underlying objective was to do everything we could to rescue these hostages, knowing that their lives were in danger, clearly in danger."

Phil Balboni, CEO of GlobalPost, the news outlet for which James Foley was working when he was kidnapped in Syria in 2012, told ABC News Foley was "moved fairly often" while in captivity.

At today's press conference Hagel went on to discuss ISIS, the brutal Sunni extremist group that has swept across Iraq in recent months and murdered James Foley, calling the group an "imminent threat" and "beyond anything we've seen."

"ISIL [ISIS] is as sophisticated and well-fund as any group we've seen. They're beyond any terrorist group," Hagel said, adding that ISIS presents a 9/11-level threat. "We must prepare for everything. The way to do that is you take a cold, steely, hard look at it and you get ready."